Crosshead-piston rod assembly for a reciprocating compressor

Abstract

A crosshead-piston rod assembly for a reciprocating compressor comprises a piston rod; a crosshead having a bore; a connection element attached to the piston rod and at least partially inserted into the bore for connecting the crosshead to a piston.

The invention claimed is: 
     
       1. A crosshead piston rod assembly for a reciprocating compressor, the crosshead piston rod assembly comprising:
 a piston rod having an abutment surface and defining a longitudinal axis; 
 a crosshead having a bore and comprising a main body; 
 a connection element attached to the piston rod and at least partially inserted into the bore for connecting the crosshead to a piston, the connection element having a first end and a second end and the piston rod having a seat for receiving the first end of the connection element; 
 a flange attached to the main body of the crosshead and defining a bore therethough; and 
 a nut attached to the second end of the connection element to fix the flange against the abutment surface of the piston rod, 
 wherein the bore of the crosshead and the bore of the flange are coaxially aligned along the longitudinal axis of the piston rod, the connection element extends through the bore of the flange, and the flange is abuttingly contacted by the nut on one end and the abutment surface of the piston rod on an opposite end such that the flange is locked between the nut and the piston rod. 
 
     
     
       2. The crosshead piston rod assembly according to  claim 1 , wherein the piston rod has a contact surface to receive the connection element, and the connection element has a gripping surface to engage the contact surface of the piston rod. 
     
     
       3. The crosshead piston rod assembly according to  claim 2 , wherein the contact surface is located inside the seat and the gripping surface is located on the first end of the connection element. 
     
     
       4. The crosshead piston rod assembly according to  claim 3 , wherein the contact surface of the piston rod comprises a female thread and the gripping surface of the connection element comprises a male thread to engage the female thread of the contact surface. 
     
     
       5. The crosshead piston rod assembly according to  claim 4  wherein the connection element comprises a male thread on the second end. 
     
     
       6. The crosshead piston rod assembly according to  claim 1 , wherein the seat is substantially cylindrical. 
     
     
       7. The crosshead piston rod assembly according to  claim 1 , wherein the connection element is coaxial with respect to the longitudinal axis of the piston rod. 
     
     
       8. The crosshead piston rod assembly according to  claim 7 , wherein the connection element is symmetrical with respect to the longitudinal axis of the piston rod. 
     
     
       9. The crosshead piston rod assembly according to  claim 1 , wherein the abutment surface of the piston rod is perpendicularly orientated relative to the longitudinal axis of the piston rod. 
     
     
       10. The crosshead piston rod assembly according to  claim 1 , wherein the flange defines holes to receive corresponding bolts to attach the flange to the main body. 
     
     
       11. The crosshead piston rod assembly according to  claim 10 , wherein the holes each define longitudinal axes that are parallel to the longitudinal axis of the piston rod. 
     
     
       12. A reciprocating compressor comprising the crosshead-piston rod assembly according to  claim 1 . 
     
     
       13. The reciprocating compressor according to  claim 12 , wherein the piston rod has a contact surface to receive the connection element, and the connection element has a gripping surface to engage the contact surface of the piston rod. 
     
     
       14. The reciprocating compressor according to  claim 12 , wherein the contact surface is located inside the seat and the gripping surface is located on the first end of the connection element. 
     
     
       15. The reciprocating compressor according to  claim 14 , wherein the contact surface of the piston rod comprises a female thread and the gripping surface of the connection element comprises a male thread for engaging the female thread of the contact surface. 
     
     
       16. The reciprocating compressor according to  claim 12 , wherein the seat is substantially cylindrical. 
     
     
       17. The reciprocating compressor according to  claim 12 , wherein the connection element is coaxial with respect to the longitudinal axis of the piston rod. 
     
     
       18. The reciprocating compressor according to  claim 17 , wherein the connection element is symmetrical with respect to the longitudinal axis of the piston rod. 
     
     
       19. A method for assembling a crosshead and a piston, the method comprising:
 providing:
 a piston rod having an abutment surface and defining a longitudinal axis; 
 a crosshead having a bore and comprising a main body; 
 a connection element attached to the piston rod and at least partially inserted into the bore for connecting the crosshead to the piston, the connection element having a first end and a second end each comprising male threads thereon, wherein the piston rod has a seat for receiving the first end of the connection element; 
 a flange attached attachable to the main body of the crosshead and defining a bore therethough; and 
 a nut; 
 
 screwing the connection element into the seat of the piston rod; 
 inserting the connection element into the bore of a flange; 
 screwing the nut onto the second end of the connection element to fix the flange against the abutment surface of the piston rod; and 
 after screwing the nut onto the second end of the connection element, fixing the flange to the main body of the crosshead, 
 wherein, when assembled, the bore of the crosshead and the bore of the flange are coaxially aligned along the longitudinal axis of the piston rod, the connection element extends through the bore of the flange, and the flange is abuttingly contacted by the nut on one end and the abutment surface of the piston rod on an opposite end such that the flange is locked between the nut and the piston rod.